Beam Trawl Invertebrates

By Marilyn LearyPosted on February 24, 2017

A little bit of everything seems to live on the ocean floor. The beam trawls give us an opportunity to see and touch some of the life that thrives in the sand and mud and gravel of the ocean floor. Identifying and describing every animal that we have pulled up would be a near-impossible task, so I have selected only a few interesting animals to meet and look at more closely.

The Parasitic Isopod

If you bottomfish, you may have seen this isopod. It almost looks like it should come from a horror movie, a mysterious creature born of the subconscious. They are usually pale and whitish, with dull eyes and sharp hooks at the ends of their legs. They are often found latched inside the gill covers of rockfish and ling cod; this individual was found outside, crawling on the eyed side of a flatfish. If you pick it up, be careful—if you hold it long enough for it to get comfortable with you, it will sink its claws into your skin.

Parsitic isopod captured in the beam trawl.

Mole Crab (Emerita analoga) Zoea

Occasionally on sandy beaches, one can find what looks like thousands of mole crabs washed up on the beach, drawing a high-water mark in the sand. These are the molts of the mole crab, the exoskeleton periodically shed to allow the animal to grow. The adults live burrowed in sandy beaches, using their antennae to collect food when water flows over them. But, they do not start life in the sand. As larvae, they drift in the ocean with the other zooplankton, eventually recruiting to the sandy shore when they metamorphose into adults. This larva is a zoea, a transparent, three-pronged creature that found its way into our net.

A mole crab (Emerita analoga) Zoea stage 5 from a net tow.

Nudibranchs

Nudibranchs (“naked gill”) are shell-less gastropods. The Pink Tritonia and Striped nudibranchs were collected along with their favorite food—sea whips and sea pens. While these individuals tended to be small, one Pink Tritonia was large and weighty—it fit snugly in the palm of my hand. I think Nudibranchs are some of the most colorful and alien-looking animals in the ocean, and many species can be found easily in the intertidal of the Oregon coast.

A Pink Tritonia nudibranch from the beam trawl.

A Striped nudibranch from the beam trawl.

A burrowing anemone from the beam trawl.

Burrowing anemone

For myself, the greatest joy of marine science is finding the thing that you have never seen before—that is so alien to you, you cannot even confidently decide how it is sorted into the tree of life. Two of these animals showed up in the trawls. The first was represented by many individuals; the color can best be described as “pink lemonade with freckles”. When first isolated from the conglomerate mass of organisms , these animals would curl into themselves; their shape was fairly non-distinct, and they looked like an odd-colored fat worm. When left alone and observed, a tiny rosette would flesh out of one end, and the animal would move it around like a head. Later, I learned it was a burrowing anemone.

I only saw one individual of the second animal. It was found at the bottom of a bucket used for sorting; when I tried to pull it out, I found that it had suctioned one end of its worm-like body to the bottom of the bucket. I had to carefully pry it loose, and even then I cannot confidently say that I did not damage it. It was bumpy and charcoal gray, one end of its body thick and the other tapered. It looks most like a peanut worm, an unsegmented marine worm that lives in burrows and uses its frilly mouth parts to collect food.

An unknown organism from the beam trawl. Perhaps it is a sea cucumber?

The Thrill of Discovery!

By Thomas MurphyPosted on February 23, 2017

Like the famous naturalists of the past, we set sail aboard the NOAA Bell M. Shimada seeking the unknown. Only this time, the unknown isn’t a dark continent or the edge to a flat world, but the unknown effects on ecological systems that are undergoing global change.

Sunrise from the bridge of the NOAA Bell M. Shimada, 21 Feb 2017.

For me, ocean surveys are a chance to reach back to the roots of this field of science – the naturalist. Just like immersion in a culture can rapidly advance one’s grasp of a foreign language, escaping the barrage of phone calls and daily emails allows for reconnecting with the real creatures and systems that many scientists now try to understand through models and complex calculations. Our sampling stations, sometimes located 200 miles off the coast of the Pacific Northwest, involve various types of nets and sensors, but ultimately, they all involve a mystery. Each tow of a net is an opportunity to see species that humans rarely would encounter, bringing a sense of reality to the myriad creatures seen on shows like Planet Earth or read about in books. At night, animals like lanternfish rise to the surface in their daily migration, having left the light of the sun as juveniles to live a life enshrouded in the murky darkness of the deep. They each represent a piece to the puzzle that drives an ever-changing ecosystem.

Neuston (surface) sample collected off Newport Hydrographic Line.

As a scientist that began my career in the warm waters of the Caribbean, these are all aliens to me. Some might even be new to science. That possibility is what inspired me as a child to pursue a career in marine biology. When the famous mountaineer George Mallory was asked why he wanted to climb Mount Everest, his response was, “Because it’s there.” For him, it was something seen that needed to be conquered through sheer will. For me, exploring the depths of the unseen world below the surface instilled a similar sentiment – to shine a light through the darkness and make the unknown known. With every copepod and fish, alga and gelatinous creature, a story unfolds about the effects of our warming oceans.

Some species, like the colonial pelagic tunicates (pyrosomes, see https://www.nwfsc.noaa.gov/news/blogs/display_blogentry.cfm?blogid=1&month=02&year=2017#blogentry115) or the Pacific pompano represent a clear sign of change in the communities of the Pacific Northwest. As their ranges expand North with warming waters, native species are experiencing new interactions and competition that has untold effects. As a salmon ecologist, both predators and prey are changing a multi-million dollar fishery. We look for answers through studying the smallest of creatures in hopes of understanding how to protect and preserve these iconic species. From changes in copepod communities, we can determine how these fish (salmon) might fare in the ocean before they make their long journeys back upriver to spawn new generations. With every net cast into the deep, we are hoping to find a way to better understand their complex lives in order to ensure future generations will be able to enjoy the bounty of the ocean we marine biologists love and treasure.

Unidentified squid species from a neuston (surface) sample.

A kelp crab from the beam trawl and a lanternfish with photophores (small silver spots along the belly) for producing light collected from a nighttime bongo net tow.

Pyrosomes:

By Samantha ZemanPosted on February 22, 2017

This unassuming tube might not look very glamorous but they have found themselves at the center of attention aboard the R/V Bell M. Shimada. This is a pyrosome, specifically Pyrosoma atlanticum, the common species in the NE Pacific (Fig. 1). Pyrosomes are pelagic Tunicates, which are part of Chordata, a phylum that includes humans. It is tough and slimy to the touch with small, pronounced bumps. Inside the wall of this gelatinous tube, which can get up to 60 cm, individual zooids are tightly packed together. These zooids have an incurrent and excurrent siphon and use cilia to pump water for feeding, respiration and movement (Fig. 2). Using a mucus net, they filter water for small planktonic microorganisms. Pyrosomes are known to aggregate in large clusters at the surface and the zooids bioluminesce to create beautiful light displays. All of this together would make for a spectacular sight underwater.

Figure 1: One of many Pyrosoma atlanticum caught in a Bongo net tow.

As bizarre as they may seem, these animals are not uncommon to those sampling off Oregon. But on our recent trip aboard the Bell M. Shimada, pyrosomes seem to be everywhere! We have been getting numerous specimens in our three different sampling gears: vertical net, Bongo net, and Beam trawl. At one of our nearshore stations, the Beam trawl brought up 2.5 gallons of pyrosomes (Fig. 3)! We were also lucky to encounter a large aggregation at the surface on the Newport Line transect. This anomalous abundance of pyrosomes has been observed in other research cruises along the West coast. A long-term time series in the California Current saw the highest catches ever of Pyrosoma atlanticum in 2015. Pyrosomes have been mystifying beachcombers up and down the coast as they wash up on beaches. These gelatinous organisms join a list of other gelatinous zooplankton, such as Aequorea spp., Doliolids, and the pteropod Corolla spectabilis, that have been seen in large numbers over the past few years.

Figure 2: Diagram of generalized pyrosome showing fluid flow and inner workings of zooids. Notice the flow of water in the colony that propels it through the water. (modified image from Invertebrate Zoology (Ruppert and Barnes, 1994; image modified by Bodegahead.blogspot.com)

As with many gelatinous zooplankton, we lack crucial insights into their natural history. So it can be difficult to tease apart how they may be impacting marine ecosystems. For instance, pyrosomes can grow rapidly and are efficient filterers with the potential to have a significant impact on phytoplankton blooms. For now, our current observations maintain that recent oceanic conditions are ideal for pyrosome populations. I’m guaranteeing this isn’t the last you’ve heard of Pyrosoma atlanticum. Stay tuned!

NCC Sampling aboard the NOAA R/V Bell M. Shimada

By Jennifer FisherPosted on February 21, 2017

We are presently out on the NOAA Ship Bell M. Shimada sampling the Northern California Current (NCC). We are a group of 8 scientists collecting routine measurements along 6 transects from Crescent City, California to Cape Meares, Oregon. Our transects extend 200 miles offshore of Newport, OR and 150 miles off Crescent City. At each station we are conducting a CTD (Conductivity, Temperature, Depth) cast to look at the water column properties (temperature, salinity, oxygen) and we are collecting plankton tows for zooplankton and ichthyoplankton (larval fish). We are also collecting water samples for phytoplankton, nutrients and chlorophyll and sampling the seafloor with a beam trawl to look for newly settled bottom fish and to characterize their habitat. Additionally, we have 2 bird observers aboard that are recording all the seabirds they observe along our journey.

We are already 4 days into our 9 day trip and the seas and our stomachs have finally calmed enough to look at a computer screen. Highlights so far include the most pyrosomes I have ever observed, which will be the focus of another blog post. The upper water column on the shelf has been quite mixed from the strong winter storms we have had. The upper water column is also fairly fresh, likely due to riverine influence. And, the surface water is also relatively cold (~10°C). It will be interesting to compare the conditions we are observing this Feb to last Feb (2016) when the El Niño and “Warm Blob” were influencing the NCC.